This invention relates generally to an isotopic separation process and, more particularly, to isotopic separation processes which employ dissociative electron attachment.
The separation of the isotope .sup.235 U (which is fissionable by neutrons) from natural uranium, a mixture containing mainly nonfissionable .sup.238 U, or simply enrichment of the mixture in .sup.235 U are extremely important processes for nuclear applications. The most commonly used process presently being employed on an industrial scale is separation by diffusion through a porous barrier. A number of other processes (electromagnetic separation employing devices derived from the mass spectrometer, for instance the so-called "calutron", separation by centrifugation, by thermal diffusion . . . ) have been used or suggested, but have not been employed for large scale operation.
A gaseous diffusion separation stage leads to a separation factor of approximately 1.004. Starting from natural uranium, for which the ratio r=.sup.235 U/.sup.238 U is of the order of 0.7%, the obtaining of a product with an r ratio equal to 3% will necessitate about 1,100 diffusion stages. Thus, any improvement in the efficiency of the enrichment process will effect considerable savings.
As previously mentioned, uranium isotope separation can be accomplished in several ways. Recently, selective photoexcitation which leads to the preferential ionization of a particular isotopic component of a gas mixture has been explored as one process for improving the efficiency of uranium enrichment. Generally, in optical isotope separation schemes there are essentially three principal steps. The first is the preferential absorption of the optical radiation to produce selective excitation or ionization of the atoms or molecules which contains the desired isotopic species. The second step is enhancement of the rates of chemical reactions or physical phenomena with involve the atoms, molecules, or ions containing the desired isotopic species as the result of their preferential absorption and excitation. The third step involves the separation of the resulting atoms, molecules, or ions as the result of the enhancement.
Various procedures for performing the first two steps for optical isotope separation have been explored, and examples can be found in the patent to J. Robieux et al, entitled "Isotopic Separation Process", U.S. Pat. No. 3,443,087, issued May 6, 1969, and application Ser. No. 599,210 by G. L. Rogoff entitled "Process For Isotope Separation Employing Cataphoresis" filed July 25, 1975. The third step which accomplishes the actual separation of the desired isotope will be dependent upon which reaction process is employed in the second step. There are several methods by which this third step can be accomplished employing either condensation, photochemical, electric field, or magnetic separation. The degree of efficiency of the third separation step will therefore be dependent upon the effectiveness of the second step in establishing an enhanced reaction which uniquely segregates the isotope of interest in a constituent form that can be easily operated upon.
Accordingly, an isotope separation process is desired which will uniquely operate on a specific isotope in a gaseous molecular mixture in a manner to transform the isotope of interest into compatible form for efficient separation.